]>
Commit | Line | Data |
---|---|---|
1b1a35ee | 1 | use crate::errors::LifetimesOrBoundsMismatchOnTrait; |
c295e0f8 | 2 | use rustc_data_structures::stable_set::FxHashSet; |
ee023bcb | 3 | use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticId, ErrorGuaranteed}; |
dfeec247 XL |
4 | use rustc_hir as hir; |
5 | use rustc_hir::def::{DefKind, Res}; | |
6 | use rustc_hir::intravisit; | |
7 | use rustc_hir::{GenericParamKind, ImplItemKind, TraitItemKind}; | |
74b04a01 | 8 | use rustc_infer::infer::{self, InferOk, TyCtxtInferExt}; |
29967ef6 | 9 | use rustc_infer::traits::util; |
f035d41b | 10 | use rustc_middle::ty; |
ba9703b0 | 11 | use rustc_middle::ty::error::{ExpectedFound, TypeError}; |
3dfed10e | 12 | use rustc_middle::ty::subst::{InternalSubsts, Subst}; |
ba9703b0 | 13 | use rustc_middle::ty::util::ExplicitSelf; |
3dfed10e | 14 | use rustc_middle::ty::{GenericParamDefKind, ToPredicate, TyCtxt}; |
dfeec247 | 15 | use rustc_span::Span; |
ba9703b0 XL |
16 | use rustc_trait_selection::traits::error_reporting::InferCtxtExt; |
17 | use rustc_trait_selection::traits::{self, ObligationCause, ObligationCauseCode, Reveal}; | |
cdc7bbd5 | 18 | use std::iter; |
85aaf69f | 19 | |
dfeec247 | 20 | use super::{potentially_plural_count, FnCtxt, Inherited}; |
60c5eb7d | 21 | |
85aaf69f SL |
22 | /// Checks that a method from an impl conforms to the signature of |
23 | /// the same method as declared in the trait. | |
24 | /// | |
25 | /// # Parameters | |
26 | /// | |
9fa01778 XL |
27 | /// - `impl_m`: type of the method we are checking |
28 | /// - `impl_m_span`: span to use for reporting errors | |
29 | /// - `trait_m`: the method in the trait | |
30 | /// - `impl_trait_ref`: the TraitRef corresponding to the trait implementation | |
dfeec247 | 31 | crate fn compare_impl_method<'tcx>( |
dc9dc135 XL |
32 | tcx: TyCtxt<'tcx>, |
33 | impl_m: &ty::AssocItem, | |
34 | impl_m_span: Span, | |
35 | trait_m: &ty::AssocItem, | |
36 | impl_trait_ref: ty::TraitRef<'tcx>, | |
37 | trait_item_span: Option<Span>, | |
38 | ) { | |
dfeec247 | 39 | debug!("compare_impl_method(impl_trait_ref={:?})", impl_trait_ref); |
85aaf69f | 40 | |
ba9703b0 | 41 | let impl_m_span = tcx.sess.source_map().guess_head_span(impl_m_span); |
2c00a5a8 | 42 | |
ee023bcb | 43 | if let Err(_) = compare_self_type(tcx, impl_m, impl_m_span, trait_m, impl_trait_ref) { |
c30ab7b3 | 44 | return; |
85aaf69f SL |
45 | } |
46 | ||
ee023bcb | 47 | if let Err(_) = compare_number_of_generics(tcx, impl_m, impl_m_span, trait_m, trait_item_span) { |
c30ab7b3 SL |
48 | return; |
49 | } | |
9e0c209e | 50 | |
ee023bcb | 51 | if let Err(_) = |
dfeec247 XL |
52 | compare_number_of_method_arguments(tcx, impl_m, impl_m_span, trait_m, trait_item_span) |
53 | { | |
85aaf69f SL |
54 | return; |
55 | } | |
56 | ||
ee023bcb | 57 | if let Err(_) = compare_synthetic_generics(tcx, impl_m, trait_m) { |
abe05a73 XL |
58 | return; |
59 | } | |
60 | ||
ee023bcb | 61 | if let Err(_) = compare_predicate_entailment(tcx, impl_m, impl_m_span, trait_m, impl_trait_ref) |
dfeec247 | 62 | { |
85aaf69f SL |
63 | return; |
64 | } | |
136023e0 | 65 | |
ee023bcb | 66 | if let Err(_) = compare_const_param_types(tcx, impl_m, trait_m, trait_item_span) { |
136023e0 XL |
67 | return; |
68 | } | |
c30ab7b3 SL |
69 | } |
70 | ||
dc9dc135 XL |
71 | fn compare_predicate_entailment<'tcx>( |
72 | tcx: TyCtxt<'tcx>, | |
73 | impl_m: &ty::AssocItem, | |
74 | impl_m_span: Span, | |
75 | trait_m: &ty::AssocItem, | |
76 | impl_trait_ref: ty::TraitRef<'tcx>, | |
ee023bcb | 77 | ) -> Result<(), ErrorGuaranteed> { |
476ff2be SL |
78 | let trait_to_impl_substs = impl_trait_ref.substs; |
79 | ||
7cac9316 XL |
80 | // This node-id should be used for the `body_id` field on each |
81 | // `ObligationCause` (and the `FnCtxt`). This is what | |
82 | // `regionck_item` expects. | |
3dfed10e | 83 | let impl_m_hir_id = tcx.hir().local_def_id_to_hir_id(impl_m.def_id.expect_local()); |
7cac9316 | 84 | |
f035d41b XL |
85 | // We sometimes modify the span further down. |
86 | let mut cause = ObligationCause::new( | |
87 | impl_m_span, | |
88 | impl_m_hir_id, | |
89 | ObligationCauseCode::CompareImplMethodObligation { | |
ee023bcb | 90 | impl_item_def_id: impl_m.def_id.expect_local(), |
476ff2be | 91 | trait_item_def_id: trait_m.def_id, |
476ff2be | 92 | }, |
f035d41b | 93 | ); |
85aaf69f SL |
94 | |
95 | // This code is best explained by example. Consider a trait: | |
96 | // | |
f035d41b XL |
97 | // trait Trait<'t, T> { |
98 | // fn method<'a, M>(t: &'t T, m: &'a M) -> Self; | |
85aaf69f SL |
99 | // } |
100 | // | |
101 | // And an impl: | |
102 | // | |
103 | // impl<'i, 'j, U> Trait<'j, &'i U> for Foo { | |
f035d41b | 104 | // fn method<'b, N>(t: &'j &'i U, m: &'b N) -> Foo; |
85aaf69f SL |
105 | // } |
106 | // | |
107 | // We wish to decide if those two method types are compatible. | |
108 | // | |
109 | // We start out with trait_to_impl_substs, that maps the trait | |
110 | // type parameters to impl type parameters. This is taken from the | |
111 | // impl trait reference: | |
112 | // | |
113 | // trait_to_impl_substs = {'t => 'j, T => &'i U, Self => Foo} | |
114 | // | |
115 | // We create a mapping `dummy_substs` that maps from the impl type | |
116 | // parameters to fresh types and regions. For type parameters, | |
117 | // this is the identity transform, but we could as well use any | |
0bf4aa26 | 118 | // placeholder types. For regions, we convert from bound to free |
85aaf69f SL |
119 | // regions (Note: but only early-bound regions, i.e., those |
120 | // declared on the impl or used in type parameter bounds). | |
121 | // | |
f035d41b | 122 | // impl_to_placeholder_substs = {'i => 'i0, U => U0, N => N0 } |
85aaf69f | 123 | // |
f035d41b | 124 | // Now we can apply placeholder_substs to the type of the impl method |
0bf4aa26 | 125 | // to yield a new function type in terms of our fresh, placeholder |
85aaf69f SL |
126 | // types: |
127 | // | |
128 | // <'b> fn(t: &'i0 U0, m: &'b) -> Foo | |
129 | // | |
130 | // We now want to extract and substitute the type of the *trait* | |
131 | // method and compare it. To do so, we must create a compound | |
132 | // substitution by combining trait_to_impl_substs and | |
f035d41b | 133 | // impl_to_placeholder_substs, and also adding a mapping for the method |
85aaf69f SL |
134 | // type parameters. We extend the mapping to also include |
135 | // the method parameters. | |
136 | // | |
f035d41b | 137 | // trait_to_placeholder_substs = { T => &'i0 U0, Self => Foo, M => N0 } |
85aaf69f SL |
138 | // |
139 | // Applying this to the trait method type yields: | |
140 | // | |
141 | // <'a> fn(t: &'i0 U0, m: &'a) -> Foo | |
142 | // | |
143 | // This type is also the same but the name of the bound region ('a | |
144 | // vs 'b). However, the normal subtyping rules on fn types handle | |
145 | // this kind of equivalency just fine. | |
146 | // | |
147 | // We now use these substitutions to ensure that all declared bounds are | |
148 | // satisfied by the implementation's method. | |
149 | // | |
150 | // We do this by creating a parameter environment which contains a | |
f035d41b XL |
151 | // substitution corresponding to impl_to_placeholder_substs. We then build |
152 | // trait_to_placeholder_substs and use it to convert the predicates contained | |
0bf4aa26 | 153 | // in the trait_m.generics to the placeholder form. |
85aaf69f SL |
154 | // |
155 | // Finally we register each of these predicates as an obligation in | |
156 | // a fresh FulfillmentCtxt, and invoke select_all_or_error. | |
157 | ||
0bf4aa26 | 158 | // Create mapping from impl to placeholder. |
f035d41b | 159 | let impl_to_placeholder_substs = InternalSubsts::identity_for_item(tcx, impl_m.def_id); |
85aaf69f | 160 | |
0bf4aa26 | 161 | // Create mapping from trait to placeholder. |
f035d41b XL |
162 | let trait_to_placeholder_substs = |
163 | impl_to_placeholder_substs.rebase_onto(tcx, impl_m.container.id(), trait_to_impl_substs); | |
164 | debug!("compare_impl_method: trait_to_placeholder_substs={:?}", trait_to_placeholder_substs); | |
85aaf69f | 165 | |
7cac9316 XL |
166 | let impl_m_generics = tcx.generics_of(impl_m.def_id); |
167 | let trait_m_generics = tcx.generics_of(trait_m.def_id); | |
168 | let impl_m_predicates = tcx.predicates_of(impl_m.def_id); | |
169 | let trait_m_predicates = tcx.predicates_of(trait_m.def_id); | |
476ff2be | 170 | |
c30ab7b3 | 171 | // Check region bounds. |
dfeec247 XL |
172 | check_region_bounds_on_impl_item( |
173 | tcx, | |
174 | impl_m_span, | |
175 | impl_m, | |
176 | trait_m, | |
177 | &trait_m_generics, | |
178 | &impl_m_generics, | |
179 | )?; | |
c30ab7b3 SL |
180 | |
181 | // Create obligations for each predicate declared by the impl | |
182 | // definition in the context of the trait's parameter | |
183 | // environment. We can't just use `impl_env.caller_bounds`, | |
184 | // however, because we want to replace all late-bound regions with | |
185 | // region variables. | |
7cac9316 XL |
186 | let impl_predicates = tcx.predicates_of(impl_m_predicates.parent.unwrap()); |
187 | let mut hybrid_preds = impl_predicates.instantiate_identity(tcx); | |
c30ab7b3 SL |
188 | |
189 | debug!("compare_impl_method: impl_bounds={:?}", hybrid_preds); | |
190 | ||
191 | // This is the only tricky bit of the new way we check implementation methods | |
192 | // We need to build a set of predicates where only the method-level bounds | |
193 | // are from the trait and we assume all other bounds from the implementation | |
194 | // to be previously satisfied. | |
195 | // | |
196 | // We then register the obligations from the impl_m and check to see | |
197 | // if all constraints hold. | |
dfeec247 XL |
198 | hybrid_preds |
199 | .predicates | |
f035d41b | 200 | .extend(trait_m_predicates.instantiate_own(tcx, trait_to_placeholder_substs).predicates); |
c30ab7b3 | 201 | |
0bf4aa26 | 202 | // Construct trait parameter environment and then shift it into the placeholder viewpoint. |
c30ab7b3 SL |
203 | // The key step here is to update the caller_bounds's predicates to be |
204 | // the new hybrid bounds we computed. | |
9fa01778 | 205 | let normalize_cause = traits::ObligationCause::misc(impl_m_span, impl_m_hir_id); |
a2a8927a XL |
206 | let param_env = ty::ParamEnv::new( |
207 | tcx.intern_predicates(&hybrid_preds.predicates), | |
208 | Reveal::UserFacing, | |
209 | hir::Constness::NotConst, | |
210 | ); | |
3c0e092e XL |
211 | let param_env = |
212 | traits::normalize_param_env_or_error(tcx, impl_m.def_id, param_env, normalize_cause); | |
7cac9316 | 213 | |
041b39d2 | 214 | tcx.infer_ctxt().enter(|infcx| { |
ba9703b0 | 215 | let inh = Inherited::new(infcx, impl_m.def_id.expect_local()); |
c30ab7b3 | 216 | let infcx = &inh.infcx; |
a7813a04 | 217 | |
f035d41b | 218 | debug!("compare_impl_method: caller_bounds={:?}", param_env.caller_bounds()); |
a7813a04 XL |
219 | |
220 | let mut selcx = traits::SelectionContext::new(&infcx); | |
221 | ||
f035d41b | 222 | let impl_m_own_bounds = impl_m_predicates.instantiate_own(tcx, impl_to_placeholder_substs); |
3c0e092e XL |
223 | for (predicate, span) in iter::zip(impl_m_own_bounds.predicates, impl_m_own_bounds.spans) { |
224 | let normalize_cause = traits::ObligationCause::misc(span, impl_m_hir_id); | |
cc61c64b | 225 | let traits::Normalized { value: predicate, obligations } = |
3c0e092e | 226 | traits::normalize(&mut selcx, param_env, normalize_cause, predicate); |
a7813a04 | 227 | |
cc61c64b | 228 | inh.register_predicates(obligations); |
ee023bcb FG |
229 | let cause = ObligationCause::new( |
230 | span, | |
231 | impl_m_hir_id, | |
232 | ObligationCauseCode::CompareImplMethodObligation { | |
233 | impl_item_def_id: impl_m.def_id.expect_local(), | |
234 | trait_item_def_id: trait_m.def_id, | |
235 | }, | |
236 | ); | |
3c0e092e | 237 | inh.register_predicate(traits::Obligation::new(cause, param_env, predicate)); |
a7813a04 | 238 | } |
85aaf69f | 239 | |
a7813a04 XL |
240 | // We now need to check that the signature of the impl method is |
241 | // compatible with that of the trait method. We do this by | |
242 | // checking that `impl_fty <: trait_fty`. | |
243 | // | |
244 | // FIXME. Unfortunately, this doesn't quite work right now because | |
245 | // associated type normalization is not integrated into subtype | |
246 | // checks. For the comparison to be valid, we need to | |
247 | // normalize the associated types in the impl/trait methods | |
248 | // first. However, because function types bind regions, just | |
249 | // calling `normalize_associated_types_in` would have no effect on | |
250 | // any associated types appearing in the fn arguments or return | |
251 | // type. | |
252 | ||
0bf4aa26 | 253 | // Compute placeholder form of impl and trait method tys. |
3157f602 | 254 | let tcx = infcx.tcx; |
476ff2be | 255 | |
c295e0f8 | 256 | let mut wf_tys = FxHashSet::default(); |
94222f64 | 257 | |
a1dfa0c6 XL |
258 | let (impl_sig, _) = infcx.replace_bound_vars_with_fresh_vars( |
259 | impl_m_span, | |
260 | infer::HigherRankedType, | |
fc512014 | 261 | tcx.fn_sig(impl_m.def_id), |
a1dfa0c6 | 262 | ); |
3157f602 | 263 | let impl_sig = |
fc512014 | 264 | inh.normalize_associated_types_in(impl_m_span, impl_m_hir_id, param_env, impl_sig); |
136023e0 | 265 | let impl_fty = tcx.mk_fn_ptr(ty::Binder::dummy(impl_sig)); |
3157f602 XL |
266 | debug!("compare_impl_method: impl_fty={:?}", impl_fty); |
267 | ||
94222f64 | 268 | // First liberate late bound regions and subst placeholders |
fc512014 | 269 | let trait_sig = tcx.liberate_late_bound_regions(impl_m.def_id, tcx.fn_sig(trait_m.def_id)); |
f035d41b | 270 | let trait_sig = trait_sig.subst(tcx, trait_to_placeholder_substs); |
3157f602 | 271 | let trait_sig = |
fc512014 | 272 | inh.normalize_associated_types_in(impl_m_span, impl_m_hir_id, param_env, trait_sig); |
c295e0f8 | 273 | // Add the resulting inputs and output as well-formed. |
94222f64 | 274 | wf_tys.extend(trait_sig.inputs_and_output.iter()); |
136023e0 | 275 | let trait_fty = tcx.mk_fn_ptr(ty::Binder::dummy(trait_sig)); |
3157f602 XL |
276 | |
277 | debug!("compare_impl_method: trait_fty={:?}", trait_fty); | |
278 | ||
dfeec247 XL |
279 | let sub_result = infcx.at(&cause, param_env).sup(trait_fty, impl_fty).map( |
280 | |InferOk { obligations, .. }| { | |
3c0e092e XL |
281 | // FIXME: We'd want to keep more accurate spans than "the method signature" when |
282 | // processing the comparison between the trait and impl fn, but we sadly lose them | |
283 | // and point at the whole signature when a trait bound or specific input or output | |
284 | // type would be more appropriate. In other places we have a `Vec<Span>` | |
285 | // corresponding to their `Vec<Predicate>`, but we don't have that here. | |
286 | // Fixing this would improve the output of test `issue-83765.rs`. | |
dfeec247 XL |
287 | inh.register_predicates(obligations); |
288 | }, | |
289 | ); | |
c30ab7b3 SL |
290 | |
291 | if let Err(terr) = sub_result { | |
dfeec247 XL |
292 | debug!("sub_types failed: impl ty {:?}, trait ty {:?}", impl_fty, trait_fty); |
293 | ||
cdc7bbd5 XL |
294 | let (impl_err_span, trait_err_span) = |
295 | extract_spans_for_error_reporting(&infcx, &terr, &cause, impl_m, trait_m); | |
dfeec247 | 296 | |
a2a8927a | 297 | cause.span = impl_err_span; |
dfeec247 XL |
298 | |
299 | let mut diag = struct_span_err!( | |
300 | tcx.sess, | |
301 | cause.span(tcx), | |
302 | E0053, | |
303 | "method `{}` has an incompatible type for trait", | |
5099ac24 | 304 | trait_m.name |
dfeec247 | 305 | ); |
cdc7bbd5 XL |
306 | match &terr { |
307 | TypeError::ArgumentMutability(0) | TypeError::ArgumentSorts(_, 0) | |
308 | if trait_m.fn_has_self_parameter => | |
309 | { | |
310 | let ty = trait_sig.inputs()[0]; | |
311 | let sugg = match ExplicitSelf::determine(ty, |_| ty == impl_trait_ref.self_ty()) | |
dfeec247 | 312 | { |
cdc7bbd5 XL |
313 | ExplicitSelf::ByValue => "self".to_owned(), |
314 | ExplicitSelf::ByReference(_, hir::Mutability::Not) => "&self".to_owned(), | |
315 | ExplicitSelf::ByReference(_, hir::Mutability::Mut) => { | |
316 | "&mut self".to_owned() | |
317 | } | |
318 | _ => format!("self: {}", ty), | |
319 | }; | |
320 | ||
321 | // When the `impl` receiver is an arbitrary self type, like `self: Box<Self>`, the | |
322 | // span points only at the type `Box<Self`>, but we want to cover the whole | |
323 | // argument pattern and type. | |
a2a8927a | 324 | let span = match tcx.hir().expect_impl_item(impl_m.def_id.expect_local()).kind { |
cdc7bbd5 XL |
325 | ImplItemKind::Fn(ref sig, body) => tcx |
326 | .hir() | |
327 | .body_param_names(body) | |
328 | .zip(sig.decl.inputs.iter()) | |
329 | .map(|(param, ty)| param.span.to(ty.span)) | |
330 | .next() | |
331 | .unwrap_or(impl_err_span), | |
332 | _ => bug!("{:?} is not a method", impl_m), | |
333 | }; | |
334 | ||
335 | diag.span_suggestion( | |
336 | span, | |
337 | "change the self-receiver type to match the trait", | |
338 | sugg, | |
339 | Applicability::MachineApplicable, | |
340 | ); | |
341 | } | |
342 | TypeError::ArgumentMutability(i) | TypeError::ArgumentSorts(_, i) => { | |
343 | if trait_sig.inputs().len() == *i { | |
344 | // Suggestion to change output type. We do not suggest in `async` functions | |
345 | // to avoid complex logic or incorrect output. | |
a2a8927a | 346 | match tcx.hir().expect_impl_item(impl_m.def_id.expect_local()).kind { |
cdc7bbd5 XL |
347 | ImplItemKind::Fn(ref sig, _) |
348 | if sig.header.asyncness == hir::IsAsync::NotAsync => | |
349 | { | |
350 | let msg = "change the output type to match the trait"; | |
351 | let ap = Applicability::MachineApplicable; | |
352 | match sig.decl.output { | |
353 | hir::FnRetTy::DefaultReturn(sp) => { | |
354 | let sugg = format!("-> {} ", trait_sig.output()); | |
355 | diag.span_suggestion_verbose(sp, msg, sugg, ap); | |
356 | } | |
357 | hir::FnRetTy::Return(hir_ty) => { | |
358 | let sugg = trait_sig.output().to_string(); | |
359 | diag.span_suggestion(hir_ty.span, msg, sugg, ap); | |
360 | } | |
361 | }; | |
362 | } | |
363 | _ => {} | |
364 | }; | |
365 | } else if let Some(trait_ty) = trait_sig.inputs().get(*i) { | |
9fa01778 | 366 | diag.span_suggestion( |
8faf50e0 | 367 | impl_err_span, |
cdc7bbd5 XL |
368 | "change the parameter type to match the trait", |
369 | trait_ty.to_string(), | |
0bf4aa26 | 370 | Applicability::MachineApplicable, |
8faf50e0 XL |
371 | ); |
372 | } | |
373 | } | |
cdc7bbd5 | 374 | _ => {} |
8faf50e0 | 375 | } |
c30ab7b3 | 376 | |
dfeec247 XL |
377 | infcx.note_type_err( |
378 | &mut diag, | |
379 | &cause, | |
380 | trait_err_span.map(|sp| (sp, "type in trait".to_owned())), | |
5099ac24 FG |
381 | Some(infer::ValuePairs::Terms(ExpectedFound { |
382 | expected: trait_fty.into(), | |
383 | found: impl_fty.into(), | |
dfeec247 XL |
384 | })), |
385 | &terr, | |
a2a8927a | 386 | false, |
dfeec247 | 387 | ); |
ee023bcb FG |
388 | |
389 | return Err(diag.emit()); | |
a7813a04 | 390 | } |
85aaf69f | 391 | |
a7813a04 XL |
392 | // Check that all obligations are satisfied by the implementation's |
393 | // version. | |
3c0e092e XL |
394 | let errors = inh.fulfillment_cx.borrow_mut().select_all_or_error(&infcx); |
395 | if !errors.is_empty() { | |
ee023bcb FG |
396 | let reported = infcx.report_fulfillment_errors(&errors, None, false); |
397 | return Err(reported); | |
85aaf69f | 398 | } |
85aaf69f | 399 | |
a7813a04 | 400 | // Finally, resolve all regions. This catches wily misuses of |
c30ab7b3 | 401 | // lifetime parameters. |
9fa01778 | 402 | let fcx = FnCtxt::new(&inh, param_env, impl_m_hir_id); |
c295e0f8 | 403 | fcx.regionck_item(impl_m_hir_id, impl_m_span, wf_tys); |
85aaf69f | 404 | |
c30ab7b3 SL |
405 | Ok(()) |
406 | }) | |
407 | } | |
408 | ||
dfeec247 | 409 | fn check_region_bounds_on_impl_item<'tcx>( |
dc9dc135 XL |
410 | tcx: TyCtxt<'tcx>, |
411 | span: Span, | |
412 | impl_m: &ty::AssocItem, | |
413 | trait_m: &ty::AssocItem, | |
414 | trait_generics: &ty::Generics, | |
415 | impl_generics: &ty::Generics, | |
ee023bcb | 416 | ) -> Result<(), ErrorGuaranteed> { |
94b46f34 XL |
417 | let trait_params = trait_generics.own_counts().lifetimes; |
418 | let impl_params = impl_generics.own_counts().lifetimes; | |
c30ab7b3 | 419 | |
dfeec247 XL |
420 | debug!( |
421 | "check_region_bounds_on_impl_item: \ | |
c30ab7b3 | 422 | trait_generics={:?} \ |
dfeec247 XL |
423 | impl_generics={:?}", |
424 | trait_generics, impl_generics | |
425 | ); | |
c30ab7b3 SL |
426 | |
427 | // Must have same number of early-bound lifetime parameters. | |
428 | // Unfortunately, if the user screws up the bounds, then this | |
429 | // will change classification between early and late. E.g., | |
430 | // if in trait we have `<'a,'b:'a>`, and in impl we just have | |
431 | // `<'a,'b>`, then we have 2 early-bound lifetime parameters | |
432 | // in trait but 0 in the impl. But if we report "expected 2 | |
433 | // but found 0" it's confusing, because it looks like there | |
434 | // are zero. Since I don't quite know how to phrase things at | |
435 | // the moment, give a kind of vague error message. | |
94b46f34 | 436 | if trait_params != impl_params { |
dfeec247 | 437 | let item_kind = assoc_item_kind_str(impl_m); |
ba9703b0 | 438 | let def_span = tcx.sess.source_map().guess_head_span(span); |
5099ac24 FG |
439 | let span = impl_m |
440 | .def_id | |
441 | .as_local() | |
442 | .and_then(|did| tcx.hir().get_generics(did)) | |
443 | .map_or(def_span, |g| g.span); | |
5869c6ff | 444 | let generics_span = tcx.hir().span_if_local(trait_m.def_id).map(|sp| { |
1b1a35ee | 445 | let def_sp = tcx.sess.source_map().guess_head_span(sp); |
5099ac24 FG |
446 | trait_m |
447 | .def_id | |
448 | .as_local() | |
449 | .and_then(|did| tcx.hir().get_generics(did)) | |
450 | .map_or(def_sp, |g| g.span) | |
5869c6ff XL |
451 | }); |
452 | ||
ee023bcb | 453 | let reported = tcx.sess.emit_err(LifetimesOrBoundsMismatchOnTrait { |
8faf50e0 | 454 | span, |
dfeec247 | 455 | item_kind, |
5099ac24 | 456 | ident: impl_m.ident(tcx), |
1b1a35ee XL |
457 | generics_span, |
458 | }); | |
ee023bcb | 459 | return Err(reported); |
85aaf69f | 460 | } |
9e0c209e | 461 | |
0bf4aa26 | 462 | Ok(()) |
c30ab7b3 | 463 | } |
9e0c209e | 464 | |
3c0e092e | 465 | #[instrument(level = "debug", skip(infcx))] |
dc9dc135 XL |
466 | fn extract_spans_for_error_reporting<'a, 'tcx>( |
467 | infcx: &infer::InferCtxt<'a, 'tcx>, | |
dc9dc135 XL |
468 | terr: &TypeError<'_>, |
469 | cause: &ObligationCause<'tcx>, | |
470 | impl_m: &ty::AssocItem, | |
dc9dc135 | 471 | trait_m: &ty::AssocItem, |
dc9dc135 | 472 | ) -> (Span, Option<Span>) { |
c30ab7b3 | 473 | let tcx = infcx.tcx; |
a2a8927a | 474 | let mut impl_args = match tcx.hir().expect_impl_item(impl_m.def_id.expect_local()).kind { |
cdc7bbd5 XL |
475 | ImplItemKind::Fn(ref sig, _) => { |
476 | sig.decl.inputs.iter().map(|t| t.span).chain(iter::once(sig.decl.output.span())) | |
c30ab7b3 SL |
477 | } |
478 | _ => bug!("{:?} is not a method", impl_m), | |
479 | }; | |
a2a8927a XL |
480 | let trait_args = |
481 | trait_m.def_id.as_local().map(|def_id| match tcx.hir().expect_trait_item(def_id).kind { | |
cdc7bbd5 XL |
482 | TraitItemKind::Fn(ref sig, _) => { |
483 | sig.decl.inputs.iter().map(|t| t.span).chain(iter::once(sig.decl.output.span())) | |
c30ab7b3 | 484 | } |
cdc7bbd5 | 485 | _ => bug!("{:?} is not a TraitItemKind::Fn", trait_m), |
a2a8927a | 486 | }); |
9e0c209e | 487 | |
cdc7bbd5 XL |
488 | match *terr { |
489 | TypeError::ArgumentMutability(i) => { | |
490 | (impl_args.nth(i).unwrap(), trait_args.and_then(|mut args| args.nth(i))) | |
491 | } | |
492 | TypeError::ArgumentSorts(ExpectedFound { .. }, i) => { | |
493 | (impl_args.nth(i).unwrap(), trait_args.and_then(|mut args| args.nth(i))) | |
c30ab7b3 | 494 | } |
48663c56 | 495 | _ => (cause.span(tcx), tcx.hir().span_if_local(trait_m.def_id)), |
c30ab7b3 SL |
496 | } |
497 | } | |
498 | ||
dc9dc135 XL |
499 | fn compare_self_type<'tcx>( |
500 | tcx: TyCtxt<'tcx>, | |
501 | impl_m: &ty::AssocItem, | |
502 | impl_m_span: Span, | |
503 | trait_m: &ty::AssocItem, | |
504 | impl_trait_ref: ty::TraitRef<'tcx>, | |
ee023bcb | 505 | ) -> Result<(), ErrorGuaranteed> { |
c30ab7b3 SL |
506 | // Try to give more informative error messages about self typing |
507 | // mismatches. Note that any mismatch will also be detected | |
508 | // below, where we construct a canonical function type that | |
509 | // includes the self parameter as a normal parameter. It's just | |
510 | // that the error messages you get out of this code are a bit more | |
511 | // inscrutable, particularly for cases where one method has no | |
512 | // self. | |
476ff2be | 513 | |
dc9dc135 | 514 | let self_string = |method: &ty::AssocItem| { |
476ff2be SL |
515 | let untransformed_self_ty = match method.container { |
516 | ty::ImplContainer(_) => impl_trait_ref.self_ty(), | |
dfeec247 | 517 | ty::TraitContainer(_) => tcx.types.self_param, |
476ff2be | 518 | }; |
fc512014 | 519 | let self_arg_ty = tcx.fn_sig(method.def_id).input(0); |
0531ce1d | 520 | let param_env = ty::ParamEnv::reveal_all(); |
abe05a73 XL |
521 | |
522 | tcx.infer_ctxt().enter(|infcx| { | |
fc512014 | 523 | let self_arg_ty = tcx.liberate_late_bound_regions(method.def_id, self_arg_ty); |
abe05a73 XL |
524 | let can_eq_self = |ty| infcx.can_eq(param_env, untransformed_self_ty, ty).is_ok(); |
525 | match ExplicitSelf::determine(self_arg_ty, can_eq_self) { | |
0bf4aa26 | 526 | ExplicitSelf::ByValue => "self".to_owned(), |
dfeec247 XL |
527 | ExplicitSelf::ByReference(_, hir::Mutability::Not) => "&self".to_owned(), |
528 | ExplicitSelf::ByReference(_, hir::Mutability::Mut) => "&mut self".to_owned(), | |
529 | _ => format!("self: {}", self_arg_ty), | |
abe05a73 XL |
530 | } |
531 | }) | |
476ff2be SL |
532 | }; |
533 | ||
ba9703b0 | 534 | match (trait_m.fn_has_self_parameter, impl_m.fn_has_self_parameter) { |
476ff2be SL |
535 | (false, false) | (true, true) => {} |
536 | ||
537 | (false, true) => { | |
538 | let self_descr = self_string(impl_m); | |
dfeec247 XL |
539 | let mut err = struct_span_err!( |
540 | tcx.sess, | |
541 | impl_m_span, | |
542 | E0185, | |
cdc7bbd5 | 543 | "method `{}` has a `{}` declaration in the impl, but not in the trait", |
5099ac24 | 544 | trait_m.name, |
dfeec247 XL |
545 | self_descr |
546 | ); | |
7cac9316 | 547 | err.span_label(impl_m_span, format!("`{}` used in impl", self_descr)); |
0731742a | 548 | if let Some(span) = tcx.hir().span_if_local(trait_m.def_id) { |
2c00a5a8 XL |
549 | err.span_label(span, format!("trait method declared without `{}`", self_descr)); |
550 | } else { | |
5099ac24 | 551 | err.note_trait_signature(trait_m.name.to_string(), trait_m.signature(tcx)); |
c30ab7b3 | 552 | } |
ee023bcb FG |
553 | let reported = err.emit(); |
554 | return Err(reported); | |
c30ab7b3 | 555 | } |
476ff2be SL |
556 | |
557 | (true, false) => { | |
558 | let self_descr = self_string(trait_m); | |
dfeec247 XL |
559 | let mut err = struct_span_err!( |
560 | tcx.sess, | |
561 | impl_m_span, | |
562 | E0186, | |
cdc7bbd5 | 563 | "method `{}` has a `{}` declaration in the trait, but not in the impl", |
5099ac24 | 564 | trait_m.name, |
dfeec247 XL |
565 | self_descr |
566 | ); | |
2c00a5a8 | 567 | err.span_label(impl_m_span, format!("expected `{}` in impl", self_descr)); |
0731742a | 568 | if let Some(span) = tcx.hir().span_if_local(trait_m.def_id) { |
7cac9316 XL |
569 | err.span_label(span, format!("`{}` used in trait", self_descr)); |
570 | } else { | |
5099ac24 | 571 | err.note_trait_signature(trait_m.name.to_string(), trait_m.signature(tcx)); |
c30ab7b3 | 572 | } |
ee023bcb FG |
573 | let reported = err.emit(); |
574 | return Err(reported); | |
c30ab7b3 | 575 | } |
c30ab7b3 SL |
576 | } |
577 | ||
578 | Ok(()) | |
579 | } | |
580 | ||
dc9dc135 XL |
581 | fn compare_number_of_generics<'tcx>( |
582 | tcx: TyCtxt<'tcx>, | |
583 | impl_: &ty::AssocItem, | |
584 | _impl_span: Span, | |
585 | trait_: &ty::AssocItem, | |
532ac7d7 | 586 | trait_span: Option<Span>, |
ee023bcb | 587 | ) -> Result<(), ErrorGuaranteed> { |
532ac7d7 XL |
588 | let trait_own_counts = tcx.generics_of(trait_.def_id).own_counts(); |
589 | let impl_own_counts = tcx.generics_of(impl_.def_id).own_counts(); | |
590 | ||
591 | let matchings = [ | |
592 | ("type", trait_own_counts.types, impl_own_counts.types), | |
593 | ("const", trait_own_counts.consts, impl_own_counts.consts), | |
594 | ]; | |
595 | ||
dfeec247 XL |
596 | let item_kind = assoc_item_kind_str(impl_); |
597 | ||
ee023bcb | 598 | let mut err_occurred = None; |
136023e0 | 599 | for (kind, trait_count, impl_count) in matchings { |
532ac7d7 | 600 | if impl_count != trait_count { |
f9f354fc | 601 | let (trait_spans, impl_trait_spans) = if let Some(def_id) = trait_.def_id.as_local() { |
a2a8927a | 602 | let trait_item = tcx.hir().expect_trait_item(def_id); |
f9f354fc XL |
603 | if trait_item.generics.params.is_empty() { |
604 | (Some(vec![trait_item.generics.span]), vec![]) | |
dc9dc135 | 605 | } else { |
f9f354fc XL |
606 | let arg_spans: Vec<Span> = |
607 | trait_item.generics.params.iter().map(|p| p.span).collect(); | |
608 | let impl_trait_spans: Vec<Span> = trait_item | |
609 | .generics | |
610 | .params | |
611 | .iter() | |
612 | .filter_map(|p| match p.kind { | |
3c0e092e | 613 | GenericParamKind::Type { synthetic: true, .. } => Some(p.span), |
f9f354fc XL |
614 | _ => None, |
615 | }) | |
616 | .collect(); | |
617 | (Some(arg_spans), impl_trait_spans) | |
618 | } | |
619 | } else { | |
620 | (trait_span.map(|s| vec![s]), vec![]) | |
621 | }; | |
9e0c209e | 622 | |
a2a8927a | 623 | let impl_item = tcx.hir().expect_impl_item(impl_.def_id.expect_local()); |
dfeec247 XL |
624 | let impl_item_impl_trait_spans: Vec<Span> = impl_item |
625 | .generics | |
626 | .params | |
627 | .iter() | |
dc9dc135 | 628 | .filter_map(|p| match p.kind { |
3c0e092e | 629 | GenericParamKind::Type { synthetic: true, .. } => Some(p.span), |
dc9dc135 | 630 | _ => None, |
dfeec247 XL |
631 | }) |
632 | .collect(); | |
dc9dc135 XL |
633 | let spans = impl_item.generics.spans(); |
634 | let span = spans.primary_span(); | |
635 | ||
532ac7d7 | 636 | let mut err = tcx.sess.struct_span_err_with_code( |
dc9dc135 | 637 | spans, |
532ac7d7 | 638 | &format!( |
dfeec247 | 639 | "{} `{}` has {} {kind} parameter{} but its trait \ |
532ac7d7 | 640 | declaration has {} {kind} parameter{}", |
dfeec247 | 641 | item_kind, |
5099ac24 | 642 | trait_.name, |
532ac7d7 | 643 | impl_count, |
60c5eb7d | 644 | pluralize!(impl_count), |
532ac7d7 | 645 | trait_count, |
60c5eb7d | 646 | pluralize!(trait_count), |
532ac7d7 XL |
647 | kind = kind, |
648 | ), | |
649 | DiagnosticId::Error("E0049".into()), | |
650 | ); | |
c30ab7b3 | 651 | |
532ac7d7 | 652 | let mut suffix = None; |
c30ab7b3 | 653 | |
dc9dc135 XL |
654 | if let Some(spans) = trait_spans { |
655 | let mut spans = spans.iter(); | |
656 | if let Some(span) = spans.next() { | |
dfeec247 XL |
657 | err.span_label( |
658 | *span, | |
659 | format!( | |
660 | "expected {} {} parameter{}", | |
661 | trait_count, | |
662 | kind, | |
663 | pluralize!(trait_count), | |
664 | ), | |
665 | ); | |
dc9dc135 XL |
666 | } |
667 | for span in spans { | |
668 | err.span_label(*span, ""); | |
669 | } | |
532ac7d7 XL |
670 | } else { |
671 | suffix = Some(format!(", expected {}", trait_count)); | |
672 | } | |
c30ab7b3 | 673 | |
dc9dc135 | 674 | if let Some(span) = span { |
dfeec247 XL |
675 | err.span_label( |
676 | span, | |
677 | format!( | |
678 | "found {} {} parameter{}{}", | |
679 | impl_count, | |
680 | kind, | |
681 | pluralize!(impl_count), | |
ba9703b0 | 682 | suffix.unwrap_or_else(String::new), |
dfeec247 XL |
683 | ), |
684 | ); | |
dc9dc135 XL |
685 | } |
686 | ||
687 | for span in impl_trait_spans.iter().chain(impl_item_impl_trait_spans.iter()) { | |
688 | err.span_label(*span, "`impl Trait` introduces an implicit type parameter"); | |
689 | } | |
c30ab7b3 | 690 | |
ee023bcb FG |
691 | let reported = err.emit(); |
692 | err_occurred = Some(reported); | |
532ac7d7 | 693 | } |
c30ab7b3 SL |
694 | } |
695 | ||
ee023bcb | 696 | if let Some(reported) = err_occurred { Err(reported) } else { Ok(()) } |
c30ab7b3 SL |
697 | } |
698 | ||
dc9dc135 XL |
699 | fn compare_number_of_method_arguments<'tcx>( |
700 | tcx: TyCtxt<'tcx>, | |
701 | impl_m: &ty::AssocItem, | |
702 | impl_m_span: Span, | |
703 | trait_m: &ty::AssocItem, | |
704 | trait_item_span: Option<Span>, | |
ee023bcb | 705 | ) -> Result<(), ErrorGuaranteed> { |
041b39d2 XL |
706 | let impl_m_fty = tcx.fn_sig(impl_m.def_id); |
707 | let trait_m_fty = tcx.fn_sig(trait_m.def_id); | |
8bb4bdeb XL |
708 | let trait_number_args = trait_m_fty.inputs().skip_binder().len(); |
709 | let impl_number_args = impl_m_fty.inputs().skip_binder().len(); | |
476ff2be | 710 | if trait_number_args != impl_number_args { |
f9f354fc | 711 | let trait_span = if let Some(def_id) = trait_m.def_id.as_local() { |
a2a8927a | 712 | match tcx.hir().expect_trait_item(def_id).kind { |
ba9703b0 | 713 | TraitItemKind::Fn(ref trait_m_sig, _) => { |
dfeec247 | 714 | let pos = if trait_number_args > 0 { trait_number_args - 1 } else { 0 }; |
0731742a XL |
715 | if let Some(arg) = trait_m_sig.decl.inputs.get(pos) { |
716 | Some(if pos == 0 { | |
717 | arg.span | |
718 | } else { | |
94222f64 | 719 | arg.span.with_lo(trait_m_sig.decl.inputs[0].span.lo()) |
0731742a | 720 | }) |
c30ab7b3 SL |
721 | } else { |
722 | trait_item_span | |
723 | } | |
724 | } | |
725 | _ => bug!("{:?} is not a method", impl_m), | |
726 | } | |
727 | } else { | |
728 | trait_item_span | |
729 | }; | |
a2a8927a | 730 | let impl_span = match tcx.hir().expect_impl_item(impl_m.def_id.expect_local()).kind { |
ba9703b0 | 731 | ImplItemKind::Fn(ref impl_m_sig, _) => { |
dfeec247 | 732 | let pos = if impl_number_args > 0 { impl_number_args - 1 } else { 0 }; |
0731742a XL |
733 | if let Some(arg) = impl_m_sig.decl.inputs.get(pos) { |
734 | if pos == 0 { | |
735 | arg.span | |
736 | } else { | |
94222f64 | 737 | arg.span.with_lo(impl_m_sig.decl.inputs[0].span.lo()) |
0731742a | 738 | } |
9e0c209e | 739 | } else { |
c30ab7b3 | 740 | impl_m_span |
9e0c209e SL |
741 | } |
742 | } | |
c30ab7b3 SL |
743 | _ => bug!("{:?} is not a method", impl_m), |
744 | }; | |
dfeec247 XL |
745 | let mut err = struct_span_err!( |
746 | tcx.sess, | |
747 | impl_span, | |
748 | E0050, | |
a2a8927a | 749 | "method `{}` has {} but the declaration in trait `{}` has {}", |
5099ac24 | 750 | trait_m.name, |
dfeec247 XL |
751 | potentially_plural_count(impl_number_args, "parameter"), |
752 | tcx.def_path_str(trait_m.def_id), | |
753 | trait_number_args | |
754 | ); | |
c30ab7b3 | 755 | if let Some(trait_span) = trait_span { |
dfeec247 XL |
756 | err.span_label( |
757 | trait_span, | |
758 | format!( | |
759 | "trait requires {}", | |
760 | potentially_plural_count(trait_number_args, "parameter") | |
761 | ), | |
762 | ); | |
7cac9316 | 763 | } else { |
5099ac24 | 764 | err.note_trait_signature(trait_m.name.to_string(), trait_m.signature(tcx)); |
9e0c209e | 765 | } |
dfeec247 XL |
766 | err.span_label( |
767 | impl_span, | |
768 | format!( | |
769 | "expected {}, found {}", | |
770 | potentially_plural_count(trait_number_args, "parameter"), | |
771 | impl_number_args | |
772 | ), | |
773 | ); | |
ee023bcb FG |
774 | let reported = err.emit(); |
775 | return Err(reported); | |
9e0c209e | 776 | } |
c30ab7b3 SL |
777 | |
778 | Ok(()) | |
85aaf69f | 779 | } |
d9579d0f | 780 | |
dc9dc135 XL |
781 | fn compare_synthetic_generics<'tcx>( |
782 | tcx: TyCtxt<'tcx>, | |
783 | impl_m: &ty::AssocItem, | |
784 | trait_m: &ty::AssocItem, | |
ee023bcb | 785 | ) -> Result<(), ErrorGuaranteed> { |
abe05a73 | 786 | // FIXME(chrisvittal) Clean up this function, list of FIXME items: |
94b46f34 | 787 | // 1. Better messages for the span labels |
abe05a73 | 788 | // 2. Explanation as to what is going on |
abe05a73 XL |
789 | // If we get here, we already have the same number of generics, so the zip will |
790 | // be okay. | |
ee023bcb | 791 | let mut error_found = None; |
abe05a73 XL |
792 | let impl_m_generics = tcx.generics_of(impl_m.def_id); |
793 | let trait_m_generics = tcx.generics_of(trait_m.def_id); | |
8faf50e0 XL |
794 | let impl_m_type_params = impl_m_generics.params.iter().filter_map(|param| match param.kind { |
795 | GenericParamDefKind::Type { synthetic, .. } => Some((param.def_id, synthetic)), | |
cdc7bbd5 | 796 | GenericParamDefKind::Lifetime | GenericParamDefKind::Const { .. } => None, |
94b46f34 | 797 | }); |
dfeec247 XL |
798 | let trait_m_type_params = trait_m_generics.params.iter().filter_map(|param| match param.kind { |
799 | GenericParamDefKind::Type { synthetic, .. } => Some((param.def_id, synthetic)), | |
cdc7bbd5 | 800 | GenericParamDefKind::Lifetime | GenericParamDefKind::Const { .. } => None, |
94b46f34 | 801 | }); |
dfeec247 | 802 | for ((impl_def_id, impl_synthetic), (trait_def_id, trait_synthetic)) in |
cdc7bbd5 | 803 | iter::zip(impl_m_type_params, trait_m_type_params) |
0bf4aa26 | 804 | { |
94b46f34 | 805 | if impl_synthetic != trait_synthetic { |
3dfed10e | 806 | let impl_hir_id = tcx.hir().local_def_id_to_hir_id(impl_def_id.expect_local()); |
dc9dc135 | 807 | let impl_span = tcx.hir().span(impl_hir_id); |
94b46f34 | 808 | let trait_span = tcx.def_span(trait_def_id); |
dfeec247 XL |
809 | let mut err = struct_span_err!( |
810 | tcx.sess, | |
811 | impl_span, | |
812 | E0643, | |
813 | "method `{}` has incompatible signature for trait", | |
5099ac24 | 814 | trait_m.name |
dfeec247 | 815 | ); |
94b46f34 XL |
816 | err.span_label(trait_span, "declaration in trait here"); |
817 | match (impl_synthetic, trait_synthetic) { | |
818 | // The case where the impl method uses `impl Trait` but the trait method uses | |
819 | // explicit generics | |
3c0e092e | 820 | (true, false) => { |
94b46f34 XL |
821 | err.span_label(impl_span, "expected generic parameter, found `impl Trait`"); |
822 | (|| { | |
823 | // try taking the name from the trait impl | |
824 | // FIXME: this is obviously suboptimal since the name can already be used | |
825 | // as another generic argument | |
dfeec247 | 826 | let new_name = tcx.sess.source_map().span_to_snippet(trait_span).ok()?; |
6a06907d XL |
827 | let trait_m = trait_m.def_id.as_local()?; |
828 | let trait_m = tcx.hir().trait_item(hir::TraitItemId { def_id: trait_m }); | |
94b46f34 | 829 | |
6a06907d XL |
830 | let impl_m = impl_m.def_id.as_local()?; |
831 | let impl_m = tcx.hir().impl_item(hir::ImplItemId { def_id: impl_m }); | |
94b46f34 XL |
832 | |
833 | // in case there are no generics, take the spot between the function name | |
834 | // and the opening paren of the argument list | |
dfeec247 XL |
835 | let new_generics_span = |
836 | tcx.sess.source_map().generate_fn_name_span(impl_span)?.shrink_to_hi(); | |
94b46f34 | 837 | // in case there are generics, just replace them |
dfeec247 XL |
838 | let generics_span = |
839 | impl_m.generics.span.substitute_dummy(new_generics_span); | |
94b46f34 | 840 | // replace with the generics from the trait |
dfeec247 XL |
841 | let new_generics = |
842 | tcx.sess.source_map().span_to_snippet(trait_m.generics.span).ok()?; | |
94b46f34 | 843 | |
9fa01778 | 844 | err.multipart_suggestion( |
94b46f34 XL |
845 | "try changing the `impl Trait` argument to a generic parameter", |
846 | vec![ | |
847 | // replace `impl Trait` with `T` | |
848 | (impl_span, new_name), | |
849 | // replace impl method generics with trait method generics | |
850 | // This isn't quite right, as users might have changed the names | |
851 | // of the generics, but it works for the common case | |
852 | (generics_span, new_generics), | |
853 | ], | |
0bf4aa26 | 854 | Applicability::MaybeIncorrect, |
94b46f34 XL |
855 | ); |
856 | Some(()) | |
857 | })(); | |
dfeec247 | 858 | } |
94b46f34 XL |
859 | // The case where the trait method uses `impl Trait`, but the impl method uses |
860 | // explicit generics. | |
3c0e092e | 861 | (false, true) => { |
94b46f34 XL |
862 | err.span_label(impl_span, "expected `impl Trait`, found generic parameter"); |
863 | (|| { | |
6a06907d XL |
864 | let impl_m = impl_m.def_id.as_local()?; |
865 | let impl_m = tcx.hir().impl_item(hir::ImplItemId { def_id: impl_m }); | |
e74abb32 | 866 | let input_tys = match impl_m.kind { |
ba9703b0 | 867 | hir::ImplItemKind::Fn(ref sig, _) => sig.decl.inputs, |
94b46f34 XL |
868 | _ => unreachable!(), |
869 | }; | |
870 | struct Visitor(Option<Span>, hir::def_id::DefId); | |
dfeec247 XL |
871 | impl<'v> intravisit::Visitor<'v> for Visitor { |
872 | fn visit_ty(&mut self, ty: &'v hir::Ty<'v>) { | |
873 | intravisit::walk_ty(self, ty); | |
874 | if let hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) = | |
875 | ty.kind | |
0bf4aa26 | 876 | { |
48663c56 | 877 | if let Res::Def(DefKind::TyParam, def_id) = path.res { |
0bf4aa26 XL |
878 | if def_id == self.1 { |
879 | self.0 = Some(ty.span); | |
94b46f34 | 880 | } |
0bf4aa26 | 881 | } |
94b46f34 XL |
882 | } |
883 | } | |
94b46f34 XL |
884 | } |
885 | let mut visitor = Visitor(None, impl_def_id); | |
886 | for ty in input_tys { | |
dfeec247 | 887 | intravisit::Visitor::visit_ty(&mut visitor, ty); |
94b46f34 XL |
888 | } |
889 | let span = visitor.0?; | |
890 | ||
dfeec247 XL |
891 | let bounds = |
892 | impl_m.generics.params.iter().find_map(|param| match param.kind { | |
8faf50e0 | 893 | GenericParamKind::Lifetime { .. } => None, |
dfeec247 | 894 | GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => { |
9fa01778 | 895 | if param.hir_id == impl_hir_id { |
8faf50e0 | 896 | Some(¶m.bounds) |
94b46f34 XL |
897 | } else { |
898 | None | |
899 | } | |
8faf50e0 | 900 | } |
dfeec247 | 901 | })?; |
8faf50e0 | 902 | let bounds = bounds.first()?.span().to(bounds.last()?.span()); |
dfeec247 | 903 | let bounds = tcx.sess.source_map().span_to_snippet(bounds).ok()?; |
94b46f34 | 904 | |
9fa01778 | 905 | err.multipart_suggestion( |
94b46f34 XL |
906 | "try removing the generic parameter and using `impl Trait` instead", |
907 | vec![ | |
908 | // delete generic parameters | |
909 | (impl_m.generics.span, String::new()), | |
910 | // replace param usage with `impl Trait` | |
911 | (span, format!("impl {}", bounds)), | |
912 | ], | |
0bf4aa26 | 913 | Applicability::MaybeIncorrect, |
94b46f34 XL |
914 | ); |
915 | Some(()) | |
916 | })(); | |
dfeec247 | 917 | } |
94b46f34 XL |
918 | _ => unreachable!(), |
919 | } | |
ee023bcb FG |
920 | let reported = err.emit(); |
921 | error_found = Some(reported); | |
abe05a73 XL |
922 | } |
923 | } | |
ee023bcb | 924 | if let Some(reported) = error_found { Err(reported) } else { Ok(()) } |
abe05a73 XL |
925 | } |
926 | ||
136023e0 XL |
927 | fn compare_const_param_types<'tcx>( |
928 | tcx: TyCtxt<'tcx>, | |
929 | impl_m: &ty::AssocItem, | |
930 | trait_m: &ty::AssocItem, | |
931 | trait_item_span: Option<Span>, | |
ee023bcb | 932 | ) -> Result<(), ErrorGuaranteed> { |
136023e0 XL |
933 | let const_params_of = |def_id| { |
934 | tcx.generics_of(def_id).params.iter().filter_map(|param| match param.kind { | |
935 | GenericParamDefKind::Const { .. } => Some(param.def_id), | |
936 | _ => None, | |
937 | }) | |
938 | }; | |
939 | let const_params_impl = const_params_of(impl_m.def_id); | |
940 | let const_params_trait = const_params_of(trait_m.def_id); | |
941 | ||
942 | for (const_param_impl, const_param_trait) in iter::zip(const_params_impl, const_params_trait) { | |
943 | let impl_ty = tcx.type_of(const_param_impl); | |
944 | let trait_ty = tcx.type_of(const_param_trait); | |
945 | if impl_ty != trait_ty { | |
946 | let (impl_span, impl_ident) = match tcx.hir().get_if_local(const_param_impl) { | |
947 | Some(hir::Node::GenericParam(hir::GenericParam { span, name, .. })) => ( | |
948 | span, | |
949 | match name { | |
950 | hir::ParamName::Plain(ident) => Some(ident), | |
951 | _ => None, | |
952 | }, | |
953 | ), | |
954 | other => bug!( | |
955 | "expected GenericParam, found {:?}", | |
956 | other.map_or_else(|| "nothing".to_string(), |n| format!("{:?}", n)) | |
957 | ), | |
958 | }; | |
959 | let trait_span = match tcx.hir().get_if_local(const_param_trait) { | |
960 | Some(hir::Node::GenericParam(hir::GenericParam { span, .. })) => Some(span), | |
961 | _ => None, | |
962 | }; | |
963 | let mut err = struct_span_err!( | |
964 | tcx.sess, | |
965 | *impl_span, | |
966 | E0053, | |
967 | "method `{}` has an incompatible const parameter type for trait", | |
5099ac24 | 968 | trait_m.name |
136023e0 XL |
969 | ); |
970 | err.span_note( | |
971 | trait_span.map_or_else(|| trait_item_span.unwrap_or(*impl_span), |span| *span), | |
972 | &format!( | |
973 | "the const parameter{} has type `{}`, but the declaration \ | |
974 | in trait `{}` has type `{}`", | |
975 | &impl_ident.map_or_else(|| "".to_string(), |ident| format!(" `{}`", ident)), | |
976 | impl_ty, | |
977 | tcx.def_path_str(trait_m.def_id), | |
978 | trait_ty | |
979 | ), | |
980 | ); | |
ee023bcb FG |
981 | let reported = err.emit(); |
982 | return Err(reported); | |
136023e0 XL |
983 | } |
984 | } | |
985 | ||
986 | Ok(()) | |
987 | } | |
988 | ||
dfeec247 | 989 | crate fn compare_const_impl<'tcx>( |
dc9dc135 XL |
990 | tcx: TyCtxt<'tcx>, |
991 | impl_c: &ty::AssocItem, | |
992 | impl_c_span: Span, | |
993 | trait_c: &ty::AssocItem, | |
994 | impl_trait_ref: ty::TraitRef<'tcx>, | |
995 | ) { | |
c30ab7b3 | 996 | debug!("compare_const_impl(impl_trait_ref={:?})", impl_trait_ref); |
d9579d0f | 997 | |
041b39d2 | 998 | tcx.infer_ctxt().enter(|infcx| { |
532ac7d7 | 999 | let param_env = tcx.param_env(impl_c.def_id); |
ba9703b0 | 1000 | let inh = Inherited::new(infcx, impl_c.def_id.expect_local()); |
cc61c64b | 1001 | let infcx = &inh.infcx; |
a7813a04 XL |
1002 | |
1003 | // The below is for the most part highly similar to the procedure | |
1004 | // for methods above. It is simpler in many respects, especially | |
1005 | // because we shouldn't really have to deal with lifetimes or | |
1006 | // predicates. In fact some of this should probably be put into | |
1007 | // shared functions because of DRY violations... | |
476ff2be | 1008 | let trait_to_impl_substs = impl_trait_ref.substs; |
a7813a04 XL |
1009 | |
1010 | // Create a parameter environment that represents the implementation's | |
1011 | // method. | |
3dfed10e | 1012 | let impl_c_hir_id = tcx.hir().local_def_id_to_hir_id(impl_c.def_id.expect_local()); |
a7813a04 | 1013 | |
0bf4aa26 | 1014 | // Compute placeholder form of impl and trait const tys. |
7cac9316 XL |
1015 | let impl_ty = tcx.type_of(impl_c.def_id); |
1016 | let trait_ty = tcx.type_of(trait_c.def_id).subst(tcx, trait_to_impl_substs); | |
f035d41b XL |
1017 | let mut cause = ObligationCause::new( |
1018 | impl_c_span, | |
1019 | impl_c_hir_id, | |
1020 | ObligationCauseCode::CompareImplConstObligation, | |
1021 | ); | |
a7813a04 | 1022 | |
cc61c64b | 1023 | // There is no "body" here, so just pass dummy id. |
dfeec247 | 1024 | let impl_ty = |
fc512014 | 1025 | inh.normalize_associated_types_in(impl_c_span, impl_c_hir_id, param_env, impl_ty); |
c30ab7b3 | 1026 | |
cc61c64b | 1027 | debug!("compare_const_impl: impl_ty={:?}", impl_ty); |
c30ab7b3 | 1028 | |
dfeec247 | 1029 | let trait_ty = |
fc512014 | 1030 | inh.normalize_associated_types_in(impl_c_span, impl_c_hir_id, param_env, trait_ty); |
c30ab7b3 | 1031 | |
cc61c64b | 1032 | debug!("compare_const_impl: trait_ty={:?}", trait_ty); |
a7813a04 | 1033 | |
dfeec247 XL |
1034 | let err = infcx |
1035 | .at(&cause, param_env) | |
1036 | .sup(trait_ty, impl_ty) | |
1037 | .map(|ok| inh.register_infer_ok_obligations(ok)); | |
d9579d0f | 1038 | |
a7813a04 | 1039 | if let Err(terr) = err { |
dfeec247 XL |
1040 | debug!( |
1041 | "checking associated const for compatibility: impl ty {:?}, trait ty {:?}", | |
1042 | impl_ty, trait_ty | |
1043 | ); | |
5bcae85e SL |
1044 | |
1045 | // Locate the Span containing just the type of the offending impl | |
a2a8927a XL |
1046 | match tcx.hir().expect_impl_item(impl_c.def_id.expect_local()).kind { |
1047 | ImplItemKind::Const(ref ty, _) => cause.span = ty.span, | |
c30ab7b3 | 1048 | _ => bug!("{:?} is not a impl const", impl_c), |
5bcae85e SL |
1049 | } |
1050 | ||
dfeec247 XL |
1051 | let mut diag = struct_span_err!( |
1052 | tcx.sess, | |
1053 | cause.span, | |
1054 | E0326, | |
cdc7bbd5 | 1055 | "implemented const `{}` has an incompatible type for trait", |
5099ac24 | 1056 | trait_c.name |
dfeec247 | 1057 | ); |
5bcae85e | 1058 | |
a2a8927a | 1059 | let trait_c_span = trait_c.def_id.as_local().map(|trait_c_def_id| { |
7cac9316 | 1060 | // Add a label to the Span containing just the type of the const |
a2a8927a | 1061 | match tcx.hir().expect_trait_item(trait_c_def_id).kind { |
7cac9316 XL |
1062 | TraitItemKind::Const(ref ty, _) => ty.span, |
1063 | _ => bug!("{:?} is not a trait const", trait_c), | |
1064 | } | |
1065 | }); | |
5bcae85e | 1066 | |
dfeec247 XL |
1067 | infcx.note_type_err( |
1068 | &mut diag, | |
1069 | &cause, | |
1070 | trait_c_span.map(|span| (span, "type in trait".to_owned())), | |
5099ac24 FG |
1071 | Some(infer::ValuePairs::Terms(ExpectedFound { |
1072 | expected: trait_ty.into(), | |
1073 | found: impl_ty.into(), | |
dfeec247 XL |
1074 | })), |
1075 | &terr, | |
a2a8927a | 1076 | false, |
dfeec247 | 1077 | ); |
5bcae85e | 1078 | diag.emit(); |
d9579d0f | 1079 | } |
cc61c64b | 1080 | |
7cac9316 XL |
1081 | // Check that all obligations are satisfied by the implementation's |
1082 | // version. | |
3c0e092e XL |
1083 | let errors = inh.fulfillment_cx.borrow_mut().select_all_or_error(&infcx); |
1084 | if !errors.is_empty() { | |
1085 | infcx.report_fulfillment_errors(&errors, None, false); | |
7cac9316 XL |
1086 | return; |
1087 | } | |
1088 | ||
9fa01778 | 1089 | let fcx = FnCtxt::new(&inh, param_env, impl_c_hir_id); |
c295e0f8 | 1090 | fcx.regionck_item(impl_c_hir_id, impl_c_span, FxHashSet::default()); |
a7813a04 | 1091 | }); |
d9579d0f | 1092 | } |
dfeec247 XL |
1093 | |
1094 | crate fn compare_ty_impl<'tcx>( | |
1095 | tcx: TyCtxt<'tcx>, | |
1096 | impl_ty: &ty::AssocItem, | |
1097 | impl_ty_span: Span, | |
1098 | trait_ty: &ty::AssocItem, | |
1099 | impl_trait_ref: ty::TraitRef<'tcx>, | |
1100 | trait_item_span: Option<Span>, | |
1101 | ) { | |
1102 | debug!("compare_impl_type(impl_trait_ref={:?})", impl_trait_ref); | |
1103 | ||
ee023bcb | 1104 | let _: Result<(), ErrorGuaranteed> = (|| { |
dfeec247 XL |
1105 | compare_number_of_generics(tcx, impl_ty, impl_ty_span, trait_ty, trait_item_span)?; |
1106 | ||
a2a8927a XL |
1107 | let sp = tcx.def_span(impl_ty.def_id); |
1108 | compare_type_predicate_entailment(tcx, impl_ty, sp, trait_ty, impl_trait_ref)?; | |
f035d41b | 1109 | |
29967ef6 | 1110 | check_type_bounds(tcx, trait_ty, impl_ty, impl_ty_span, impl_trait_ref) |
dfeec247 XL |
1111 | })(); |
1112 | } | |
1113 | ||
1114 | /// The equivalent of [compare_predicate_entailment], but for associated types | |
1115 | /// instead of associated functions. | |
f035d41b | 1116 | fn compare_type_predicate_entailment<'tcx>( |
dfeec247 XL |
1117 | tcx: TyCtxt<'tcx>, |
1118 | impl_ty: &ty::AssocItem, | |
1119 | impl_ty_span: Span, | |
1120 | trait_ty: &ty::AssocItem, | |
1121 | impl_trait_ref: ty::TraitRef<'tcx>, | |
ee023bcb | 1122 | ) -> Result<(), ErrorGuaranteed> { |
dfeec247 XL |
1123 | let impl_substs = InternalSubsts::identity_for_item(tcx, impl_ty.def_id); |
1124 | let trait_to_impl_substs = | |
1125 | impl_substs.rebase_onto(tcx, impl_ty.container.id(), impl_trait_ref.substs); | |
1126 | ||
1127 | let impl_ty_generics = tcx.generics_of(impl_ty.def_id); | |
1128 | let trait_ty_generics = tcx.generics_of(trait_ty.def_id); | |
1129 | let impl_ty_predicates = tcx.predicates_of(impl_ty.def_id); | |
1130 | let trait_ty_predicates = tcx.predicates_of(trait_ty.def_id); | |
1131 | ||
1132 | check_region_bounds_on_impl_item( | |
1133 | tcx, | |
1134 | impl_ty_span, | |
1135 | impl_ty, | |
1136 | trait_ty, | |
1137 | &trait_ty_generics, | |
1138 | &impl_ty_generics, | |
1139 | )?; | |
1140 | ||
1141 | let impl_ty_own_bounds = impl_ty_predicates.instantiate_own(tcx, impl_substs); | |
1142 | ||
1143 | if impl_ty_own_bounds.is_empty() { | |
1144 | // Nothing to check. | |
1145 | return Ok(()); | |
1146 | } | |
1147 | ||
1148 | // This `HirId` should be used for the `body_id` field on each | |
1149 | // `ObligationCause` (and the `FnCtxt`). This is what | |
1150 | // `regionck_item` expects. | |
3dfed10e | 1151 | let impl_ty_hir_id = tcx.hir().local_def_id_to_hir_id(impl_ty.def_id.expect_local()); |
f035d41b XL |
1152 | let cause = ObligationCause::new( |
1153 | impl_ty_span, | |
1154 | impl_ty_hir_id, | |
1155 | ObligationCauseCode::CompareImplTypeObligation { | |
ee023bcb | 1156 | impl_item_def_id: impl_ty.def_id.expect_local(), |
dfeec247 XL |
1157 | trait_item_def_id: trait_ty.def_id, |
1158 | }, | |
f035d41b | 1159 | ); |
dfeec247 XL |
1160 | |
1161 | debug!("compare_type_predicate_entailment: trait_to_impl_substs={:?}", trait_to_impl_substs); | |
1162 | ||
1163 | // The predicates declared by the impl definition, the trait and the | |
1164 | // associated type in the trait are assumed. | |
1165 | let impl_predicates = tcx.predicates_of(impl_ty_predicates.parent.unwrap()); | |
1166 | let mut hybrid_preds = impl_predicates.instantiate_identity(tcx); | |
1167 | hybrid_preds | |
1168 | .predicates | |
1169 | .extend(trait_ty_predicates.instantiate_own(tcx, trait_to_impl_substs).predicates); | |
1170 | ||
1171 | debug!("compare_type_predicate_entailment: bounds={:?}", hybrid_preds); | |
1172 | ||
1173 | let normalize_cause = traits::ObligationCause::misc(impl_ty_span, impl_ty_hir_id); | |
a2a8927a XL |
1174 | let param_env = ty::ParamEnv::new( |
1175 | tcx.intern_predicates(&hybrid_preds.predicates), | |
1176 | Reveal::UserFacing, | |
1177 | hir::Constness::NotConst, | |
1178 | ); | |
dfeec247 XL |
1179 | let param_env = traits::normalize_param_env_or_error( |
1180 | tcx, | |
1181 | impl_ty.def_id, | |
1182 | param_env, | |
1183 | normalize_cause.clone(), | |
1184 | ); | |
1185 | tcx.infer_ctxt().enter(|infcx| { | |
ba9703b0 | 1186 | let inh = Inherited::new(infcx, impl_ty.def_id.expect_local()); |
dfeec247 XL |
1187 | let infcx = &inh.infcx; |
1188 | ||
f035d41b | 1189 | debug!("compare_type_predicate_entailment: caller_bounds={:?}", param_env.caller_bounds()); |
dfeec247 XL |
1190 | |
1191 | let mut selcx = traits::SelectionContext::new(&infcx); | |
1192 | ||
1193 | for predicate in impl_ty_own_bounds.predicates { | |
1194 | let traits::Normalized { value: predicate, obligations } = | |
fc512014 | 1195 | traits::normalize(&mut selcx, param_env, normalize_cause.clone(), predicate); |
dfeec247 XL |
1196 | |
1197 | inh.register_predicates(obligations); | |
1198 | inh.register_predicate(traits::Obligation::new(cause.clone(), param_env, predicate)); | |
1199 | } | |
1200 | ||
1201 | // Check that all obligations are satisfied by the implementation's | |
1202 | // version. | |
3c0e092e XL |
1203 | let errors = inh.fulfillment_cx.borrow_mut().select_all_or_error(&infcx); |
1204 | if !errors.is_empty() { | |
ee023bcb FG |
1205 | let reported = infcx.report_fulfillment_errors(&errors, None, false); |
1206 | return Err(reported); | |
dfeec247 XL |
1207 | } |
1208 | ||
1209 | // Finally, resolve all regions. This catches wily misuses of | |
1210 | // lifetime parameters. | |
1211 | let fcx = FnCtxt::new(&inh, param_env, impl_ty_hir_id); | |
c295e0f8 | 1212 | fcx.regionck_item(impl_ty_hir_id, impl_ty_span, FxHashSet::default()); |
dfeec247 XL |
1213 | |
1214 | Ok(()) | |
1215 | }) | |
1216 | } | |
1217 | ||
f035d41b XL |
1218 | /// Validate that `ProjectionCandidate`s created for this associated type will |
1219 | /// be valid. | |
1220 | /// | |
1221 | /// Usually given | |
1222 | /// | |
1223 | /// trait X { type Y: Copy } impl X for T { type Y = S; } | |
1224 | /// | |
1225 | /// We are able to normalize `<T as X>::U` to `S`, and so when we check the | |
1226 | /// impl is well-formed we have to prove `S: Copy`. | |
1227 | /// | |
1228 | /// For default associated types the normalization is not possible (the value | |
1229 | /// from the impl could be overridden). We also can't normalize generic | |
1230 | /// associated types (yet) because they contain bound parameters. | |
94222f64 | 1231 | #[tracing::instrument(level = "debug", skip(tcx))] |
29967ef6 | 1232 | pub fn check_type_bounds<'tcx>( |
f035d41b XL |
1233 | tcx: TyCtxt<'tcx>, |
1234 | trait_ty: &ty::AssocItem, | |
1235 | impl_ty: &ty::AssocItem, | |
1236 | impl_ty_span: Span, | |
1237 | impl_trait_ref: ty::TraitRef<'tcx>, | |
ee023bcb | 1238 | ) -> Result<(), ErrorGuaranteed> { |
f035d41b XL |
1239 | // Given |
1240 | // | |
1241 | // impl<A, B> Foo<u32> for (A, B) { | |
1242 | // type Bar<C> =... | |
1243 | // } | |
1244 | // | |
94222f64 XL |
1245 | // - `impl_trait_ref` would be `<(A, B) as Foo<u32>> |
1246 | // - `impl_ty_substs` would be `[A, B, ^0.0]` (`^0.0` here is the bound var with db 0 and index 0) | |
1247 | // - `rebased_substs` would be `[(A, B), u32, ^0.0]`, combining the substs from | |
1248 | // the *trait* with the generic associated type parameters (as bound vars). | |
1249 | // | |
1250 | // A note regarding the use of bound vars here: | |
1251 | // Imagine as an example | |
1252 | // ``` | |
1253 | // trait Family { | |
1254 | // type Member<C: Eq>; | |
1255 | // } | |
1256 | // | |
1257 | // impl Family for VecFamily { | |
1258 | // type Member<C: Eq> = i32; | |
1259 | // } | |
1260 | // ``` | |
1261 | // Here, we would generate | |
1262 | // ```notrust | |
1263 | // forall<C> { Normalize(<VecFamily as Family>::Member<C> => i32) } | |
1264 | // ``` | |
1265 | // when we really would like to generate | |
1266 | // ```notrust | |
1267 | // forall<C> { Normalize(<VecFamily as Family>::Member<C> => i32) :- Implemented(C: Eq) } | |
1268 | // ``` | |
1269 | // But, this is probably fine, because although the first clause can be used with types C that | |
1270 | // do not implement Eq, for it to cause some kind of problem, there would have to be a | |
1271 | // VecFamily::Member<X> for some type X where !(X: Eq), that appears in the value of type | |
1272 | // Member<C: Eq> = .... That type would fail a well-formedness check that we ought to be doing | |
1273 | // elsewhere, which would check that any <T as Family>::Member<X> meets the bounds declared in | |
1274 | // the trait (notably, that X: Eq and T: Family). | |
1275 | let defs: &ty::Generics = tcx.generics_of(impl_ty.def_id); | |
1276 | let mut substs = smallvec::SmallVec::with_capacity(defs.count()); | |
1277 | if let Some(def_id) = defs.parent { | |
1278 | let parent_defs = tcx.generics_of(def_id); | |
1279 | InternalSubsts::fill_item(&mut substs, tcx, parent_defs, &mut |param, _| { | |
1280 | tcx.mk_param_from_def(param) | |
1281 | }); | |
1282 | } | |
1283 | let mut bound_vars: smallvec::SmallVec<[ty::BoundVariableKind; 8]> = | |
1284 | smallvec::SmallVec::with_capacity(defs.count()); | |
1285 | InternalSubsts::fill_single(&mut substs, defs, &mut |param, _| match param.kind { | |
1286 | GenericParamDefKind::Type { .. } => { | |
1287 | let kind = ty::BoundTyKind::Param(param.name); | |
1288 | let bound_var = ty::BoundVariableKind::Ty(kind); | |
1289 | bound_vars.push(bound_var); | |
1290 | tcx.mk_ty(ty::Bound( | |
1291 | ty::INNERMOST, | |
1292 | ty::BoundTy { var: ty::BoundVar::from_usize(bound_vars.len() - 1), kind }, | |
1293 | )) | |
1294 | .into() | |
1295 | } | |
1296 | GenericParamDefKind::Lifetime => { | |
1297 | let kind = ty::BoundRegionKind::BrNamed(param.def_id, param.name); | |
1298 | let bound_var = ty::BoundVariableKind::Region(kind); | |
1299 | bound_vars.push(bound_var); | |
1300 | tcx.mk_region(ty::ReLateBound( | |
1301 | ty::INNERMOST, | |
1302 | ty::BoundRegion { var: ty::BoundVar::from_usize(bound_vars.len() - 1), kind }, | |
1303 | )) | |
1304 | .into() | |
1305 | } | |
1306 | GenericParamDefKind::Const { .. } => { | |
1307 | let bound_var = ty::BoundVariableKind::Const; | |
1308 | bound_vars.push(bound_var); | |
5099ac24 | 1309 | tcx.mk_const(ty::ConstS { |
94222f64 XL |
1310 | ty: tcx.type_of(param.def_id), |
1311 | val: ty::ConstKind::Bound( | |
1312 | ty::INNERMOST, | |
1313 | ty::BoundVar::from_usize(bound_vars.len() - 1), | |
1314 | ), | |
1315 | }) | |
1316 | .into() | |
1317 | } | |
1318 | }); | |
1319 | let bound_vars = tcx.mk_bound_variable_kinds(bound_vars.into_iter()); | |
1320 | let impl_ty_substs = tcx.intern_substs(&substs); | |
1321 | ||
f035d41b XL |
1322 | let rebased_substs = |
1323 | impl_ty_substs.rebase_onto(tcx, impl_ty.container.id(), impl_trait_ref.substs); | |
1324 | let impl_ty_value = tcx.type_of(impl_ty.def_id); | |
1325 | ||
3dfed10e XL |
1326 | let param_env = tcx.param_env(impl_ty.def_id); |
1327 | ||
1328 | // When checking something like | |
f035d41b | 1329 | // |
3dfed10e XL |
1330 | // trait X { type Y: PartialEq<<Self as X>::Y> } |
1331 | // impl X for T { default type Y = S; } | |
f035d41b | 1332 | // |
3dfed10e XL |
1333 | // We will have to prove the bound S: PartialEq<<T as X>::Y>. In this case |
1334 | // we want <T as X>::Y to normalize to S. This is valid because we are | |
1335 | // checking the default value specifically here. Add this equality to the | |
1336 | // ParamEnv for normalization specifically. | |
1337 | let normalize_param_env = { | |
1338 | let mut predicates = param_env.caller_bounds().iter().collect::<Vec<_>>(); | |
29967ef6 XL |
1339 | match impl_ty_value.kind() { |
1340 | ty::Projection(proj) | |
1341 | if proj.item_def_id == trait_ty.def_id && proj.substs == rebased_substs => | |
1342 | { | |
1343 | // Don't include this predicate if the projected type is | |
1344 | // exactly the same as the projection. This can occur in | |
1345 | // (somewhat dubious) code like this: | |
1346 | // | |
1347 | // impl<T> X for T where T: X { type Y = <T as X>::Y; } | |
1348 | } | |
1349 | _ => predicates.push( | |
94222f64 XL |
1350 | ty::Binder::bind_with_vars( |
1351 | ty::ProjectionPredicate { | |
1352 | projection_ty: ty::ProjectionTy { | |
1353 | item_def_id: trait_ty.def_id, | |
1354 | substs: rebased_substs, | |
1355 | }, | |
5099ac24 | 1356 | term: impl_ty_value.into(), |
29967ef6 | 1357 | }, |
94222f64 XL |
1358 | bound_vars, |
1359 | ) | |
29967ef6 XL |
1360 | .to_predicate(tcx), |
1361 | ), | |
1362 | }; | |
a2a8927a XL |
1363 | ty::ParamEnv::new( |
1364 | tcx.intern_predicates(&predicates), | |
1365 | Reveal::UserFacing, | |
1366 | param_env.constness(), | |
1367 | ) | |
f035d41b | 1368 | }; |
94222f64 XL |
1369 | debug!(?normalize_param_env); |
1370 | ||
1371 | let impl_ty_substs = InternalSubsts::identity_for_item(tcx, impl_ty.def_id); | |
1372 | let rebased_substs = | |
1373 | impl_ty_substs.rebase_onto(tcx, impl_ty.container.id(), impl_trait_ref.substs); | |
f035d41b XL |
1374 | |
1375 | tcx.infer_ctxt().enter(move |infcx| { | |
a2a8927a | 1376 | let inh = Inherited::new(infcx, impl_ty.def_id.expect_local()); |
f035d41b XL |
1377 | let infcx = &inh.infcx; |
1378 | let mut selcx = traits::SelectionContext::new(&infcx); | |
1379 | ||
3dfed10e | 1380 | let impl_ty_hir_id = tcx.hir().local_def_id_to_hir_id(impl_ty.def_id.expect_local()); |
5099ac24 FG |
1381 | let normalize_cause = ObligationCause::new( |
1382 | impl_ty_span, | |
1383 | impl_ty_hir_id, | |
1384 | ObligationCauseCode::CheckAssociatedTypeBounds { | |
ee023bcb | 1385 | impl_item_def_id: impl_ty.def_id.expect_local(), |
5099ac24 FG |
1386 | trait_item_def_id: trait_ty.def_id, |
1387 | }, | |
1388 | ); | |
3c0e092e XL |
1389 | let mk_cause = |span: Span| { |
1390 | let code = if span.is_dummy() { | |
1391 | traits::MiscObligation | |
1392 | } else { | |
1393 | traits::BindingObligation(trait_ty.def_id, span) | |
1394 | }; | |
1395 | ObligationCause::new(impl_ty_span, impl_ty_hir_id, code) | |
29967ef6 | 1396 | }; |
f035d41b | 1397 | |
29967ef6 XL |
1398 | let obligations = tcx |
1399 | .explicit_item_bounds(trait_ty.def_id) | |
1400 | .iter() | |
1401 | .map(|&(bound, span)| { | |
94222f64 | 1402 | debug!(?bound); |
29967ef6 XL |
1403 | let concrete_ty_bound = bound.subst(tcx, rebased_substs); |
1404 | debug!("check_type_bounds: concrete_ty_bound = {:?}", concrete_ty_bound); | |
f035d41b | 1405 | |
29967ef6 XL |
1406 | traits::Obligation::new(mk_cause(span), param_env, concrete_ty_bound) |
1407 | }) | |
1408 | .collect(); | |
1409 | debug!("check_type_bounds: item_bounds={:?}", obligations); | |
f035d41b | 1410 | |
29967ef6 | 1411 | for mut obligation in util::elaborate_obligations(tcx, obligations) { |
f035d41b XL |
1412 | let traits::Normalized { value: normalized_predicate, obligations } = traits::normalize( |
1413 | &mut selcx, | |
3dfed10e | 1414 | normalize_param_env, |
f035d41b | 1415 | normalize_cause.clone(), |
fc512014 | 1416 | obligation.predicate, |
f035d41b | 1417 | ); |
f035d41b | 1418 | debug!("compare_projection_bounds: normalized predicate = {:?}", normalized_predicate); |
29967ef6 | 1419 | obligation.predicate = normalized_predicate; |
f035d41b XL |
1420 | |
1421 | inh.register_predicates(obligations); | |
29967ef6 | 1422 | inh.register_predicate(obligation); |
f035d41b XL |
1423 | } |
1424 | ||
1425 | // Check that all obligations are satisfied by the implementation's | |
1426 | // version. | |
a2a8927a | 1427 | let errors = inh.fulfillment_cx.borrow_mut().select_all_or_error(&infcx); |
3c0e092e | 1428 | if !errors.is_empty() { |
ee023bcb FG |
1429 | let reported = infcx.report_fulfillment_errors(&errors, None, false); |
1430 | return Err(reported); | |
f035d41b XL |
1431 | } |
1432 | ||
1433 | // Finally, resolve all regions. This catches wily misuses of | |
1434 | // lifetime parameters. | |
1435 | let fcx = FnCtxt::new(&inh, param_env, impl_ty_hir_id); | |
29967ef6 | 1436 | let implied_bounds = match impl_ty.container { |
c295e0f8 | 1437 | ty::TraitContainer(_) => FxHashSet::default(), |
29967ef6 XL |
1438 | ty::ImplContainer(def_id) => fcx.impl_implied_bounds(def_id, impl_ty_span), |
1439 | }; | |
c295e0f8 | 1440 | fcx.regionck_item(impl_ty_hir_id, impl_ty_span, implied_bounds); |
f035d41b XL |
1441 | |
1442 | Ok(()) | |
1443 | }) | |
1444 | } | |
1445 | ||
dfeec247 XL |
1446 | fn assoc_item_kind_str(impl_item: &ty::AssocItem) -> &'static str { |
1447 | match impl_item.kind { | |
1448 | ty::AssocKind::Const => "const", | |
ba9703b0 | 1449 | ty::AssocKind::Fn => "method", |
f035d41b | 1450 | ty::AssocKind::Type => "type", |
dfeec247 XL |
1451 | } |
1452 | } |